1. Field of the Invention
The invention relates to a roller-type antifriction bearing intended to be fitted to a pulling system of a weaving loom and to a pulling system comprising such a bearing.
2. Brief Description of the Related Art
A weaving loom shed forming device generally comprises several heald frames individually actuated by a pulling system. The pulling system comprises a collection of link rods and levers for each heald frame, the collections being mounted in parallel in a confined space.
The elements of the pulling system are articulated to one another at pivot connections made using ball bearings or roller bearings. The latter type of bearing has a higher load-bearing capability than ball bearings. These bearings take up a limited amount of axial space because of the relatively fine way in which the space housing the collections is split up. Bearing maintenance is made more complicated because of the difficulty in accessing these bearings which generally are sited under the heald frames and relatively far apart.
EP-A-0 437 896 describes a sealed roller bearing with a relatively limited load bearing capability. The problem is that the bearing end plates which axially guide the rollers are relatively thick, thus reducing the axial length of the rollers and therefore their load bearing capability. In addition, the lip of each lateral seal lies radially level with the rollers which means that it can be pushed aside by the grease displaced from the raceways during operation. This loss of lubricant means that the bearing requires relatively frequent maintenance and its life is limited.
EP-A-0 602 711 describes a sealed roller bearing pushed into the bore of a male part consisting of a lever or a shed adjusting fastener like the one described in EP-A- 0 744 482. The load bearing capability of a roller bearing such as this is also limited by the relatively great thickness of its end plates. What is more, the end plates are coated with a layer of rubber belonging to a lip seal and the axial size of which also reduces the maximum possible length of the rollers and therefore their load bearing capability.
Moreover, in the antifriction bearing described in EP-A-0 602 711, the lubricant has a restricted free volume because this is limited merely to the gaps between the rollers. Now, these gaps are swept by the rollers as the bearing oscillates, which means that the lubricant is very highly stressed and therefore has a short life.
DE-A-1 965 0731 describes a roller bearing comprising two end plates which are positioned on the flanks of the rollers and which each define a lubricating cavity. The end plates, secured to one race of the bearing, are mounted with axial clearance with respect to lateral flanges thus giving them a certain mobility. Because of these clearances, the axial compactness of the bearing is not ideal. Furthermore, the end plates are subjected to axial loads, exerted by the rollers, without being able to transmit these loads to the flanges. These axial loads are therefore fully or partially reacted by the connection between the end plates and the race, and this may damage the end plates, their connection and/or adversely affect the sealing of the rollers. Furthermore, the antifriction bearing described in DE-A- 1 965 0731 does not include any special sealing means which means that it needs to be topped up with lubricant fairly regularly.